Asbestos product



Dec. 15, 1942. R. E. PARRY 2,305,488

ASBESTOS PRODUCT Filed Jan; 5, 193a INVENTOR. R. OBERT PARRY.

ATTORNEY.

plane of the Patented Dec. 15, 1942' 2,305,488 ASBESTOS raonuo'r Robert E. Parry,

Manyille, N. J., assignor to Johns-Manville Corporation, New York, N. Y., a corporation of New York Application January 5, 1938, Serial No. 183,426

4 Claims.

smooth-faced asbestos sheet by calendering in special manner. The invention \comprises, also,

, the application to asbestos paper of a flexible coloring composition. permitting flexing of the;

during use, as well as applying a profilm over the said composition.

the product resulting paper tective the invention comprises from-the method described herein.

The product ,of the present invention is useful for a variety of purposes requiring a smooth-surample, wall covering, other building material, or heat insulation. Because of the special desirability of the product for heat insulation, the invention will be illustrated by detailed description in connection therewith.

It is an object of the invention to provide an insulating, decorative, washable, and preferably grease/resistant article, such as covering .for

hot water tanks, steam pipes of relatively low 'Other 39 temperature, water lines, or the likeobjects "and advantages will appear from thedescription of the inventiorr.

Forthe purpose of illustration, the invention willbe described in connection with the attached drawing. 3

Fig.1 shows in elevation an edge view of an asbestos paper product made inaccordance with the invention.

Fig. 2 is a perspective view of my improved Further,

around the pipe.

' faced or decorative asbestos product, as, for exheat insulation partly assembled around a pipe 40 to be insulated.

'Fig. 3 shows diagramm tically a side elevational view of apparatus usedin the calendering step of my method.

There is shown me matted asbestos fibres and, interspersed therewith, fibrous clots or other lumps H, individually of thickness greater than the thickness of the finished paper. The clots or lumps on one side,

face of the paper and, on the-other side, extend beyond the plane of the'back of the paper. g

Applied to the relatively smooth face of the, paper is the coating l2 of coloring composition fibres in the paper beater.

a sheet of ipaper l0 contain- 4 lie approximately flush withthe 5 over which there preferably extends a'continuous film l3 of protective material of kind to be described later. I

The heat insulating assembly of Fig. 2 includes the pipe l4 and tubular insulation therearound The insulation comprises a composite of sheets l5 of asbestos paper or the like. The several sheets of paper are, suitably, spaced apart, as by alternating corrugated sheets with sheets of regular surface.

The outer layer of the insulating material is the asbestos paper iii of generally regular surface (as -distinguished from corrugated or indented).

The tubularinsulation is. provided .with a hinge-like joint l'l formed by the saw kerf extending longitudinally of the section and. nearly but not quite throug the layer of insulating material, from the in ide towards the outside thereof. At a longitudinal position that may be approximately opposite the joint, there is discontinuityof the layer of insulating material, at position l8, so that the tubular material may be opened upon the joint I! and then closed by being brought together at l8, after insertion Bands l9 may be used to hold the insulation around the pipe.

In making my product, I first form an asbestos paper by methods and machinery that are conventional, except as noted.

Care is taken to disperse well the fibres, as, for instance, by passage of ordinary, commercially milled asbestos through an additional'wil low machine of usual type, in which the milling action is caused by a series of rapidly rotated, pivotally mounted metal bars or hammers. The machine is provided with a grating below the rotating hammers and with means for forcing a draft of air upwardly through the grating and the hammer chamber. Unmilled asbestos particles terid to move downwardly through the grating and to be eliminated, whereas the ,well dispersed fibres are carried upwardly and out of the mill, by means of the. air stream.

The well dispersed asbestos fibres so produced are then made into paper. Admixtures may be made to the dilute aqueous suspension of the Thus, there may be added /a binder, organic fibres, and a water-repellent material, all in proportions that are usual in asbestos paper manufacture for heat insulation.. V p Water repellence may be imparted as described in U. S.'Patent 1,972,500 issued to Toohey and Williams on September 4, 1934.

regular surface of cylindrical shape.

The proportion of water-repellent material should be small, so. as to preserve the penetrability of the paper to liquid water but make such penetration veryslow. A typical proportion of such added ingredients is as follows: starch binder 2 to 4%, sulfite wood pulp 12 to 20%, and well dispersed, emulsified parafiin wax-2 to 5%, the percentages being parts dry weight of the several ingredients on the dry weight of the paper. One or more of the admixtures may be omitted if its function is not desired.

The mixture is felted (matted) and finished into paper. The paperis then formed into range boiler covering, pipe covering, or the like by usual methods and machines. For example, a portion of the paper may be corrugated ,or indented and then composited with alternating sheets of the paper of plane surface, so that adjacent sheets are spaced apart by the irregularities'of surface of the indented or corrugated paper. The composited sheets are adhered by a suitable adhesive, as, for instance, sodium silicate. Tubular pipe covering may be made from my special paper generally as described in United States Patents 1,444,395 ,1 1,444,396, and 1,444,397, to Seigle. The hinge joint I1 and severance at the zone l8 may be formed as described in United States Patent 2,051,076 to De'akin. However, the; outer insulating sheet, of generally regular sur-" face, is decoratively coated preferably before being applied. as a part of the tube or other insulating article.

. in the finished paper as irregularities of surface.

These irregularities are exaggerated in conspicuousness when the paper containing such irregularities is given a relatively smooth coating of coloring composition.

To obviate this difflculty, a special method and calender have been devised, to smooth the face of the paper to which the coloring composition is to be applied. The calender includes a hard calender roller 2|, suitably of chilled iron or hardened steel, having a carefully ground and Coacting with this roller is a juxtaposed roller having an exterior portion that is relatively soft and resil-.

iently yieldable. This roller 21 has suitably an iron orsteel core 23. Its exterior is rubbery and, suitably, is composed of a layer 24 of vulcanized rubber composition, neoprene composition, or the like. This layer is of substantial thickness,

' say, one-fourth to one inch, so that it may be dented, but only temporarily, by the clots, grit, or lumps found in the asbestos paper. The rubbery composition used should be one that feels holes or shiny spots that do not take a coating properly.

The paper is next coated over its smooth face by the coloring composition applied in fluent, hardenable condition. The composition is then hardened, after which there is applied the protecting film I 3 of lacquer or the like which extends continuously over the coating composition l2.

Because the finished article ordinarily is flexed during use or during installation in the position of use, the coating composition selected is one that, when dry, will be flexible without cracking. This requirement is particularly severe; the pipe covering shown in Fig. 2, when being installed around the pipe, must be opened at a sharp angle along the joint l1, without cracking or marring the appearance of the coating.

I have found that a suitable coating is one containing an intimate mixture of a binder and a flexibility-imparting agent (flexibilizing agent).

This agent should be one that can be mixed intimately with the fluent binder composition and that will provide a high degreeof flexibility to the finished coating. Such an agent is rubber.

Another is polymerized chloroprene of rubbery consistency (neoprene).- When the binder is used in an aqueous composition, the flexibilizing agent is added to the saidcomposition in the form of an aqueous-dispersion, of which latex is an example. I

, Variousbinders, that is, vehicles may be used in the coloring composition. The binder should be one that will become anchored properly to the asbestos paper to which it is applied and that will not deteriorate at an appreciable rate during use of the insulation with the coating in place on the outside thereof. Also, the binder is preferably one that, in conjunction with the other ingredients, imparts a fair degree of viscosity to the finished composition for coating,

so that the composition will bridge over minor. irregularities on the face of the to which the composition is applied.

Of the vehicles having these general properties, the preferred one is casein. When casein is used, it is dispersed in water, advantageously with the aid of a small proportion of an alkaline salt, in accordance with usual practice. Starch or glue may be used when water-resistance of the binder is not necessary; they maybe dispersed in warm hard to the touch but which may be dented readily by the finger nail. In a typical calender assembly, the rolls may be each about 12-16 in. in

diameter. Usual calender pressures are applied, under which pressure the rubber-surfaced roller is flattened or dished slightly at the bight between the two rollers. The paper to be calendered is passed between the rollers. On issuing from the calender, the paper has a relatively smooth surface formed by the roller 2! and a rough'back, clots and lumps having been forced backwardly in the paper..

In contrast with this result, calendering in ordinary manner presses the clots, developing water, for being mixed with the other ingredients and applied to thepaper.

The flexibilizing agent, such as latex or a similar dispersion of neoprene in water, is mixed with binder solution or dispersion. Usual compounding ingredients may-be present, as, for instance,

vulcanizing and/or 'antioxidation agents. Into .the aqueous composition thereare also admixed flllers or pigments to establish the desired opacity or color.

For decorative effect, the coating composition should include pigmentary material, this term including fillers and pigments. Such materials that may be used are satin white (a white powder including lime and alum as raw materials), flne clay, titanium oxide pigment, and/or zinc oxide. If a color other than white is desired, then there are used pigments of desired color that are non' reactive with the other-ingredients of the com-. position.

Also, there may be used a smoothing agent, such, for example, as a small proportion of a high boiling mineral oil or paraflin wax, this asbestos paper film, giving, also, some waterproofing.

to establish the opacityfand color;

agent in addition to its smoothing effect on the In a typical coating composition there have been used about 2 to v ably 3 parts, of rubber in the form of latex to 1 part of casein, in conjunction with about 25 to 35 parts of fillers and pigments, the pigments of high coloring capacity, such as titanium oxide, being about 2 to 5 parts to 1 of the casein. Into this composition, before application to the asbestos. paper, there was also admixed about 2 parts of parafiin wax, as the waterproofing and smoothing agent, and to parts of water in addition to the water in the latex.

In another coating composition there were pres-. ent, for each part of casein, about 5 parts of rubber, in the form of a 60% latex solution, 0.1 part soda ash, and 0.04 part ammonium hydroxide, along with 4 parts of water in addition to the water in the latex.

In making the composition, the casein is suitably dissolved first. Thus, it is soaked for a half hour or so with a part of the water that is to be present in the finished composition along with the selected alkaline material to increase the solubility of the casein, as, for ence of the sodium carbonate and ammonium hydroxide above specified. The mixture is then heated to a moderately elevated temperature, say, to about 140 'to 160 F., and stirred until the casein is dissolved or dispersed. Then. there are added the remainder of the water, the dispersion of the flexibilizing agent, and fillers and pigments The smoothing agent is then added and the whole thoroughly mixed.

The coloring composition, made, for example, as described above, is applied to asbestos paper. In using asbestos paper that has been calendered on one side against the hard roller and on the other against a yieldable applied tothe face that has been smoothed by contact with the hard roller.

The coating may be made by a conventional machine and method. Thus, it ,may be spread continuously upon the paper by means of a re verse roller coating machine. In such a machine, the coloring composition is supplied as a layer instance, in the pres- 4 parts by weight, prefermay serve as .the outside layer of asbestos paper of the articles described in the said patents to Seigle and to Deakin or of flexible composites of spaced sheets of asbestos paper of large area and design adapting them to be shaped around cylindrical tanks, such as range boilers. ,i

In'such use, however,-there is difflcillty due to spotting off the otherwise attractive colored coatbacking, the coating is of regulated thickness to a roller which is rotated preciably by the color of the paper which is coated.

The coating on the paper is then hardened, as by evaporation of the volatile extender therm'n. Using the aqueous casein coating composition,

' hardening is effected by evaporation of water.

This evaporation may be effectedat a moderately elevated temperature, in a typical paper drier, say, of the festoon type, in which the coating is kept free from contacts until'aiter it is dried.

Other methods of application of the coating include the use of revolving or oscillating brushes or of a coating knife, each in a conventional assembly.

The coated insulating article, insulating element the'article is in use.

paper is then .composited into the so that it constitutes the outer of the insulating article when Thus, the coated paper 7 is the fact thatthere limited to any theory access of air to The greatest smoothness of er insulating element I preferably n'elatively stiff, as distinguished from ing, when the coating is handled with the hands or otherwise subjected to soiling conditions.

To obviate this difficulty when it exists, the coloring composition should be protected by a film of lacquer or the like which is substantially impermeable to grease or to acidic material present in perspiration. When the coating composition includesan ingredient that deteriorates in the presence of air, as, for instance, rubber, then the protective film should also be substantially air-impermeable, so as to minimize the the said ingredient. should be water-washable without injury. V

I have used. to advantage a protective film of pyroxylin lacquer of the kind ordinarily used in'coating paper. Other protective films may be used, as, for instance, one containing as the chief film-forming ingredient vinylite or cellulose acetate, dissolved for application in usual solvent mixtures for the said ingredient of selected kind.

The lacquer may be applied to advantage with a reverse roll coating machine or as is described above, for the coating. t g

After the lacquer is applied,hardening is produced by the evaporation of the volatile extenders or solvents originally present.

In addition to the calendering that has been described, the article may tionally, either 'enihg of the coloring composition or after the application and hardening of the protective film. the finished article is obtained. when calendering is done before the coating with the coloring composition, after the coating, and also after thelacquering. Calendering the paper bearing the hardened coloring coating tends to smooth the coating and force it firmly into the outer portions of the paper. calendering after the hardening of the protective film serves to smooth and polish the film.

The asbestos paper, to scribed is applied and which constitutes the outof my finished article, is

papers that are limp. The stiffness of the paper should be such that it will preserve its generally regular shape, whether cylindrical or plane, when applied oveiportions of an insulating article that are not smooth. Illustrating the degree of stiffness of the paper which carries the coating is best used asbestos paper weighing '7 to 12 pounds to square feet of the paper, the paper including the starch binder and admixed wood pulp in about the proportions illustrated numerically above. v

The oating composition containingcas "in as the vehicle or hinder adheres partic'ularl well to asbestos paper. e the invention isnot of explanation of the re-. sults obtained, it is considered probable that the adherence of the casein to the asbestos is improved to a ,large extent-by chemical reaction of the casein with the basic ingredients of'the asbestos fibres and the consequent integral union of that part of the casein with paper.

be calendered addiafter the application and hard-.

which the coating de the fibres of the bilizing agentmay be prevulcanized. Thus, there may be used, as the source of rubber, a prevulcanized latex, such as Vultex.

The product so made is attractive in color,

' gloss, and regularity of the exposed face. Particularly because of the use of the small proportion of water-repellent material in .the asbestos paper, the aqueous coating composition during application and drying does not sink into the paper excessively but stands up on the surface, with' the production of a I substantially smooth,.continu ous film. Because of the flexible nature of the coating. in final, hardened form, an article containing the coatin may be flexedrepeatedly and sharply, without cracking.

The details given are for the purpose of illustration, not restriction, and variations within the spirit of the invention are intended to be included in the scope of the appended claims.

What I claim is: y

1. A flexible tubular heat insulating article of generally regular outer surface, the tube being severed longitudinally along one side so that it may be opened and applied around a curved surfaceto be insulated and then closed around said surface, comprising a gmposite of a plurality of sheets of asbestos pape and a coating of coloring composition applied over the exposed face of the outer one of the sheets, the said composition including an intimate mixture of casein, a flexibility-imparting agent, and a .pigmentary material.

2. Heat insulating pipe covering comprising a tube of composited sheets of asbestos. paper, a hinge-like joint extending longitudinally of the tube, the tube being severed longitudinally at a position approximately opp site the said joint so that the tube may .be opened for insertion around a pipe and then closed, and aflexlble pigmented'casein composition extending as a coat: ing over the said outer sheet and joint.

3. Heat insulating pipe covering comprising a tube having' a generally regular outer surface and including composited sheets of asbestos paper, a hinge-like Joint extending longitudinally of the tube, the tube being severed longitudinally at a position approximately opposite the said Joint so as to permit the tube to be opened for insertion around a pipe. and then to be closed, a flexible composition containing an in-.

timate mixture of casein and rubber extending as a coating over the outer asbestos sheet and joint and a film of substantially air-impermeable,

grease-impermeable, and water-washable material extending continuously over the flexible coeting.

4. An article of manufacture as described in claim f3, the said coating composition including rubber and casein in the proportion of approximately 3 parts of rubber to 1 of casein.

Rbima'r E. PARRY. 

